Work with multiple data sources ( 29- 32)
fix different union fields
different structure-remove or keep (null values) different data field names- rename and merge
HOW TO create union
drag tables to add UNDER OG table - # rows should increase - use ctrl to select multiple reference fields- help identify source of data (sheet and table name)
HOW TO create relationship
drag tables to data source pane will auto connect if comment field name
HOW TO open physical layer
field dropdown menu
TIPS unions
-1st table added = "root" -CAN join union tables- can use table name/sheet -CANT add/edit after publishing - merge mismatched nulls/field
blend
-REQUIRES common DIMENSION -blue = primary/ orange= additional -works like left join (all from primary and additional from others) -different worksheets can have different primaries -field added to view first = primary -cANT be published **never truly combine data , query each data source independently - can handle different data source types
WILDCARD union
-auto adds field to union when file names meet criteria -good when expecting similar data files in future (like yrs, days)
TIPS relationships
-drag most detailed table to canvas first -can readjust dragged location by dragging -CANT edit relationships after publishing -no data duplication (unlike JOINS)
relationships
-dynamic flexible way to combine data from multiple tables for analysis -default way to work with data from multiple tables -created directly on data source canvas -single data source answer variety of business questions
JOIN using common field
-extends table horizontally -can be full outer -created in physical layer of tableau -CANT edit after publishing -duplications (aggregations incorrect)
union
-only method of appending rows - "lengthen" -combine data of similar structures -logical layer -includes duplicates
MANUAL union
-select specific data sheets/tables to combine -must come from same connection -cannot make union tables from different databases
USES for blends
-specific linking fields (or # fields) vary on sheet by sheet basis -want primary source to vary sheet by sheet -using data sources that cant be combined with relationship -combine published data sources unavailable to edit
data model
if more than 2-3 tables shows how tables related to match business scenario ER DIAGRAM
new union method
will appear in connection pane of data source if applicable double click -> drag+drop into window
